//第十章的编程题目练习使用指针对数组进行运算
//计算每年的总降水量，年平均降水量，5年中每月的平均降水量。
#include <stdio.h>
#define MONTHS 12
#define YRS 5

int main(void)
{
	const float rain[YRS][MONTHS] =
	{
	  {4.3,4.3,4.3,3.0,2.0,1.2,0.2,0.2,0.4,2.4,3.5,6.6},
      {8.5,8.2,1.2,1.6,2.4,0.0,5.2,0.9,0.3,0.9,1.4,7.3},
      {9.1,8.5,6.7,4.3,2.1,0.8,0.2,0.2,1.1,2.3,6.1,8.4},
      {7.2,9.9,8.4,3.3,1.2,0.8,0.4,0.0,0.6,1.7,4.3,6.2},
      {7.6,5.6,3.8,2.8,3.8,0.2,0.0,0.0,0.0,1.3,2.6,5.2}
	};
	int year, month;
	float subtot, total;

	printf(" YEAR RAINFALL (inches)\n");
	for (year = 0, total = 0; year < YRS; year++)
	{ /* for each year, sum rainfall for each month */
		for (month = 0, subtot = 0; month < MONTHS; month++)
			subtot += *(*(rain + year) + month);
		printf("%5d %15.1f\n", 2010 + year, subtot);
		total += subtot; /* total for all years */
	}
	printf("\nThe yearly average is %.1f inches.\n\n", total / YRS);
	printf("MONTHLY AVERAGES:\n\n");
	printf(" Jan Feb Mar Apr May Jun Jul Aug Sep Oct ");
	printf(" Nov Dec\n");

	for (month = 0; month < MONTHS; month++)
	{ /* for each month, sum rainfall over years */
		for (year = 0, subtot = 0; year < YRS; year++)
			subtot += *(*(rain + year) + month);
		printf("%4.1f ", subtot / YRS);
	}
	printf("\n");
	return 0;
}